The present invention relates to visual displays, and more particularly to on-screen displays.
Typical graphical user interfaces in personal computer (PC) and workstation applications use selectively shaded borders to produce the effect of shadowed boxes around selected fields in order to highlight these fields to the user, and thus make the interface more ergonomic. Manipulation of the borders of these boxes can be chosen such that the box bordering the icon or text appears either raised or depressed, depending upon whether the top, bottom, and sides are shaded light or dark.
Computer applications typically create these effects using software, as opposed to hardware. However, graphical user interfaces are used by simple on-screen displays type devices that are used as the primary adjustment interfaces for PC monitors and television sets. The graphical user interfaces associated with on-screen displays are created and controlled by a controller indigenous to the monitor or television set. The controller typically creates the graphical user interface by a simple character generator, using a predetermined character set, and a small amount of page random access memory (RAM). The page RAM holds the information that defines the screen page that will be displayed. To reduce memory requirements, the page RAM contains character identifiers, such as an ASCII code, which reference a character set preprogrammed in ROM. The character set in the ROM contains the actual graphical pixel representation of each character.
As with computer applications, it is also desirable to simulate the shadowed box effect with graphical user interfaces associated with on-screen displays. The KS2501 xe2x80x9cOSD Processor for Monitorxe2x80x9d manufactured by Samsung uses three control bits at each character location in the page RAM to define how the box should by constructed.
Although providing a shadow box effect, the KS2501 has a number of disadvantages. Addition of three control bits per character position requires larger amounts of page RAM which is costly. Additionally, graphical limitations are imposed on the character boxes such that a box can only enclose a single line and must be rectangular in shape. The box also overwrites pixel information in the left and right columns and the top and bottom rows of the character. Finally, programming the controller becomes more complex when boxing a string of characters as the controller has to decide which box characteristic to use for every individual character.
Accordingly, it would be advantageous if the shadow box effect of the graphical user interface for an on-screen display could be generated which uses less page RAM.
It also would be advantageous if the shadow box effect of the graphical user interface for an on-screen display could be generated which permits more different types and shapes of boxes.
It also would be advantageous if the shadow box effect of the graphical user interface for an on-screen display could be generated which overwrites less pixel i information from each character.
It also would be advantageous if the shadow box effect of the graphical user interface for an on-screen display could be generated which requires less complex controller programming for implementation.
The present invention is directed to a system, method, and apparatus for displaying a character on the screen of monitor or television. A display controller fetches the contents from a memory location in page random access memory (RAM) to determine the character, color palette, and character attributes to be displayed. The contents of the memory location are used to fetch a graphical representation of the character from a character read only memory, a color palette from the color palette lockup, and an enhanced feature register from an attribute table. The attributes are implemented by overwriting the graphical representation of the character, based on the enhanced features of the character and the enhanced features of at least a second character.